Database systems have been proposed to process queries on encrypted data. Some such database systems employ the principle of not changing the database query processing operators, and instead, adapt the encryption method. Consequently, for many query types, e.g., range queries, such database systems rely on order-preserving encryption.
Next to the functionality of the query processing, security and performance of database systems are of equal importance. Accordingly, the security of order-preserving encryption is of concern. In some examples, order-preserving encryption schemes are provided that are as secure as possible. However, how secure such order-preserving encryption schemes are against crypto attacks, e.g. known plaintext attacks, remains unclear.